Milling apparatus for removing a given amount of material from parts satisfying a geometric requirement



United States Patent [72] Inventors John A. Mayer,

Tonawanda; Mitchell J. Banas, North Tonawanda; Robert E. Willer, Tonawanda, NY.

[2i] Appl. No. 794,185

[22] Filed Jan. 27, 1969 [45] Patented Oct. 6, 1970 I73] Assignee Brighton Tool & Die Design, Inc.,

Tonawanda, XX.

[54] MILLING APPARATUS FOR REMOVING A GIVEN AMOUNT OF MATERIAL FROM PARTS SATISFYING A GEOMETRIC REQUIREMENT I8 Claims, 44 Drawing Figs.

[52] U.S.CI 90/11,

[51 Int. Cl 1323f 23/08,

B23c 3/00 [50] Field of Search 90/56, 15.]. I l. 14:77/64: Sl/(Consulted) [56] References Cited UNITED STATES PATENTS 3,008,382 lI/I96l Hawleyetal 90/15.]

Primary Examiner-Gil Weidenfeld Armrney- Christel and Bean ABSTRACT: Parts to be machined, for example used welding electrodes, are received by a loading mechanism which senses the orientation of each part and places properly oriented parts in a disc-shaped holding member. The memberis incrementally rotated at predetermined intervals by controlled drive means A probe mechanism includes a first member which is moved into contact with the end of the part to be machined and a second member which is moved into contact with a point on the part spaced from that end, for example the inner end wall of the cooling recess in a welding electrode. Only those parts in which this measured distance is equal to or greater than a predetermined amount are operated on further by the apparatus. In one embodiment, the apparatus includes a milling machine of the type wherein the amount of material removed from each part depends upon the distance between the end of the part and a point on the milling machine housing. This distance is controlled by a stop member threadably connected in the holding member in conjunction with a mechanism for rotating the stop member an amount depending upon the location of the end of the part. In another embodiment, the milling machine is provided with a sensor for indicating the start of the machining operation and means for controlling the number of revolutions of a rotary cutting tool included therein.

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MILLING APPARATUS FOR REMOVING A GIVEN AMOUNT OF MATERIAL FROM PARTS SATISFYING A GEOMETRIC REQUIREMENT BACKGROUND OF THE INVENTION the worn surfaces thereof. By way of illustration the present invention will be described with particular reference to dressing" of welding electrodes, although the principles of the invention can be variously applied.

Welding electrodes are generally tubular in shape with a relatively thick end wall providing the operating surface at one end thereof. These electrodes also have an internal bore which extends through the opposite end in a direction generally parallel to the longitudinal axis and terminates in an end wall surface spaced from the operating surface. The internal bore receives a flow ofcoolant during welding.

Welding electrodes have been remachined or "dressed by hand in conjunction with machines such as a lathe. Such semiautomatic operation is not completely satisfactory because it does not consistently result in proper alignment of the renewed operating surface with respect to the electrode longitudinal axis. When alignment is improper the electrode, in addition to not complying with safety regulations, produces a weld of inferior quality. If this operation could be performed entirely by machine, the characteristic consistency and speed of machines would provide the highly desirable and previously unobtainable results of a larger volume of finished parts con sistently having proper alignment.

The peculiar requirements imposed on renewed or "dress ed electrodes. however. give rise to several challenging machine design problems needed to be solved before fully automatic operation could result. Safety regulations, for example, prohibit the remachining of any electrode in which the distance between the worn operating surface or end to be machined and the end wall of the interior recess is less than a predetermined, safe distance. To comply further with safety regulations and in order to prolong the electrode life as much as possible, it is required that only a predetermined or minimal amount of material be removed from the end of each electrode. This requirement -renders machine design difficult because of the variations in length among electrodes. Moreover, since one and only one end of the electrode is to be machined, automatic feeding and loading ofa plurality of randomly oriented electrodes into the machine, properly oriented, gives rise to another difficult problem.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a machine for removing a portion of the material at one end ofa part so as to provide a properly finished and aligned surface at thatend.

It is a further object of this invention to provide such a machine which will operate only on parts wherein the distance between the end from which material is to be removed and a point on the part spaced therefrom is equal to or greater than a predetermined amount.

It is a further object of this invention to provide such a machine wherein a predetermined or minimal amount of material will be removed from each part regardless of the length thereof.

It is a further object of this invention to provide such a machine wherein a plurality of randomly oriented parts are loaded therein and properly oriented with respect to the end which is to be machined.

It is a more particular object of this invention to provide a machine for dressing or remachining the worn surface ends of welding electrodes, so that the newsurface is properly aligned, by removing only a predetermined or minimal amount of material from each electrode, regardless of length, and only from those electrodes having a given, safe amount of material at the worn surface end.

It is a further object of this invention to provide such a machine for receiving a plurality of randomly oriented electrodes and placing them in proper orientation for operation by the machine.

The present invention provides novel apparatus wherein a plurality of randomly oriented parts, only one end of each of which is to be machined, are received, the orientation of each is sensed, and those properly oriented are placed in a mechanism for conveying the parts through the operational stages or stations of the apparatus. The distance between the end to be machined, of each part, and a point on the part spaced therefrom is measured, and the apparatus operates further on only those parts in which thedistance is equal to or greater than a predetermined amount. In one embodiment, the apparatus includes a milling machine of the type-wherein the amount of material removed from each part depends upon the distance between the end of the part and a point on the milling machine housing. This distance is adjusted for each part so that a given amount of material is removed from each part regardless of the length thereof. In another embodiment, the apparatus includes a milling machine of the type wherein the number of revolutions of the rotary cutting mechanism included therein is controlled. Contact between the cutting mechanism and the part is sensed and initiates operation of the mechanism so that a given amount of material isremoved from each part regardless of the length thereof.

These and other advantages and characterizing features of the present invention will become apparent from the following description of two illustrative embodiments thereof, considered in conjunction with the accompanying drawings wherein like numerals represent like parts throughout the various views.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. I is a side elevational view of an apparatus of the present invention with a portion of the housing removed;

FIG. 2 is a cross-sectional view thereof the apparatus taken about on the line 2-2 ofFIG. 1;

FIG. 3 is an enlarged, fragmentary sectional view thereof taken about on line 3-3 of FIG. 2 and showing in detail a component of the part holding means provided by this invention;

FIG. 4 is an elevational view taken about on line 4-4 of FIG.

FIG. 5 is an elevational view ofa conventional welding electrode in new or unused condition;

FIG. 6 shows the electrode of FIG. 5 after being used;

FIG. 7 shows the electrode of FIG. 6 after being renewed or dressed" by the apparatus of the present invention;

FIG. 8 shows an electrode which is rejected by the apparatus of the present invention because of its geometric characteristics;

FIG. 9 is an enlarged, fragmentary plan view of the apparatus of FIG. I showing the loading mechanism provided thereby;

FIG. 10 is a side elevational view of the loading mechanism shown in FIG. 9;

FIG. 11 is a fragmentary sectional view taken about on the line 11-11 of FIG. 10

FIG. 12 is a sectional view taken about on line 12-12 of FIG. 9;

FIGS. 13-16 are schematic illustrations of the operation of a portion of the loading mechanism on a properly oriented part;

FIGS. 17-20 are schematic illustrations of the operation of the same portion of the loading mechanism on an improperly oriented part;

FIG. 21 is a fragmentary elevational view of a mechanism provided by this invention for insuring that the same amount of material is removed from each part regardless of the length thereof;

FIG. 22 is an elevational view thereof taken about on the line 22-22 of FIG. 21;

FIG. 23 is an elevational view thereof taken about on the line 23-23 of FIG. 21;

FIG. 24 is a sectional view thereof taken about on line 24-24 of FIG. 23;

FIG. 25 is a fragmentary elevational view of the probe mechanism included in the apparatus of FIG. 1;

FIG. 26 is an elevational view thereof taken about on line 26-26 of FIG. 25;

FIG. 27 is a fragmentary sectional view thereof taken about on line 27-27 of FIG. 25;

FIG. 28 is a schematic representation of the operation of a portion of the probe mechanism of FIGS. 2527;

FIG. 29 is a fragmentary elevational view of a reject mechanism which can be included in the apparatus of this invention;

FIG. 30 is a fragmentary elevational view of an eject mechanism which can be included in the apparatus of this invention;

FIG. 31 is a fragmentary elevational view of the apparatus of the present invention showing the milling machine included therein;

FIG. 32 is a sectional view thereof taken about on line 32-32 of FIG. 31;

FIG. 33 is a sectional view thereof taken about on line 33-33 of FIG. 32;

FIG. 34 is an enlarged fragmentary view similar to FIG. 31 with parts removed;

Fig. 35 is a fragmentary elevational view showing a reset mechanism which can be included in the apparatus provided by this invention;

FIG. 36 is a fragmentary elevational view showing an ar rangement for cleaning the holding means included in the apparatus of this invention;

FIG. 37 is a schematic representation of the various operations performed by the apparatus of this invention on a part during a cycle;

FIG. 38 is a timing diagram of the various operations represented in FIG. 37;

FIG. 39 is a fragmentary elevational view of a modification of the apparatus of this invention;

FIG. 40 is a sectional view thereof taken about on line 40-40 of FIG. 39;

FIG. 41 is a sectional view thereof taken about on line 41-41 of FIG. 40;

FIGS. 42 and 43 are schematic representations of the various operations performed by the modified apparatus of this invention on a part during a cycle; and

FIG. 44 shows a fluid circuit for controlling and operating various components of the apparatus ofthis invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS The apparatus provided by this invention, in general, may be used to remove a given amount of material from one end of a part of machinable material regardless of its length and only if the part has a given geometric characteristic. One particularly advantageous use of the apparatus is for remachining or dressing" welding electrodes, and a conventional electrode in new or unused condition is shown in FIG. 5. It includes a generally cylindrical body portion 11 having an operating surface 12 at one end, in this particular illustration at the lefthand end, and a generally narrower and tapered portion 13 at the other end thereof. A bore 14 is provided in the interior of the electrode for receiving a liquid coolant such as water. FIG. 6 shows such an electrode after having been used in welding for a particular time, and the most apparent difference is that the outermost end of the operating surface, here designated 12, is worn away. FIG. 7 shows the same electrode after having been remachined or dressed by the apparatus provided by this invention. The operating surface. here designated 12''. is again substantially of the same shape as that of the new electrode shown in FIG. 5, but a portion of the cylindrical portion 1 1 has been removed with the result that the overall length of the electrode is slightly reduced. FIG. 8 shows an electrode 10"which does not satisfy safety requirements in that the distance between the worn surface end, here designated 16, and a particular point spaced therefrom, in the present instance the inner end wall 15 of the recess 14, is less than a predetermined, minimum amount. One important feature of the apparatus of the present invention, as will be explained presently, is that this critical distance is sensed or measured for each electrode and only those electrodes in which this distance is equal to or greater than a predetermined amount will be operated on. In addition, to comply with safety regulations and to insure that the electrode life is prolonged as much as possible, it is required that only a predetermined or minimum amount of material be removed from the electrode. Another important feature, therefore, is that the apparatus of the present invention removes the same, predetermined amount of material from each electrode regardless of the length thereof.

A brief description of the various functions provided by the apparatus of the present invention will facilitate an understanding of the structure and overall operation thereof. Referring momentarily to FIG. 37, there is seen schematically represented a holding means 20 which grips the parts to be machined, such as the welding electrodes previously described, and moves the parts to and from various stations in the machine at which particular mechanisms operate on the parts. The holding means 20 preferably carries the parts through a circular path under the operation of controlled drive means (not shown) which move the means 20 through various increments at predetermined intervals. An indexing mechanism, indicated schematically at 21, initiates operation of the various mechanisms in response to the arrival of the parts at the stations by means of the movements of the holding means 20. One particular arrangement for sensing these movements includes a limit switch 22 which is activated by a plurality of stops 23 provided on the holding means. The limit switch, in turn, is connected through line 24 in controlling relation to the indexing mechanism 21. Thus, as the parts are taken through each increment of the path, in this example a circular path, the indexing mechanism 21 functions, under control of the limit switch 22, to initiate operation of the mechanisms at the various stations in the machine in response to the arrival of the part at the stations. It should be noted that the arrangement of switch 22, stops 23 and line 24 are merely illustrative of many various arrangements whereby the arrival of a part at a station, caused by movement of the holding means, is indicated and communicated to the indexing mechanism, which arrangements would be included within the spirit and scope of the invention.

In FIG. 37 eight stations are identified at which various operations are performed on the part. The particular mechanisms for performing these operations, however, are not shown, but various components such as fluid cylinders controlled by solenoid-operated valves and limit switches which control the operation of these mechanisms are represented schematically. The operation of these components will be described further on in the specification. The first or load" station is indicated generally at the upper righthand corner ofthe diagram. At this station the parts are transported from a storage means and those parts which are properly oriented are loaded into the holding means 20 so as to be firmly gripped thereby, whereas the remaining parts are rejected and reconveyed to the storage means. In a counterclockwise direction around the diagram, the next or second station is designated "setup". Here an adjustment is made in the distance between the end of the part, such as a Welding electrode, which is to be machined and the end of a stop 

